Clark Damon A, Grant Lars C
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Proc Natl Acad Sci U S A. 2005 Jun 28;102(26):9150-5. doi: 10.1073/pnas.0407659102. Epub 2005 Jun 20.
Swimming bacteria detect chemical gradients by performing temporal comparisons of recent measurements of chemical concentration. These comparisons are described quantitatively by the chemotactic response function, which we expect to optimize chemotactic behavioral performance. We identify two independent chemotactic performance criteria: In the short run, a favorable response function should move bacteria up chemoattractant gradients; in the long run, bacteria should aggregate at peaks of chemoattractant concentration. Surprisingly, these two criteria conflict, so that when one performance criterion is most favorable, the other is unfavorable. Because both types of behavior are biologically relevant, we include both behaviors in a composite optimization that yields a response function that closely resembles experimental measurements. Our work suggests that the bacterial chemotactic response function can be derived from simple behavioral considerations and sheds light on how the response function contributes to chemotactic performance.
游动的细菌通过对化学物质浓度的近期测量进行时间比较来检测化学梯度。这些比较由趋化反应函数进行定量描述，我们期望该函数能优化趋化行为表现。我们确定了两个独立的趋化性能标准：短期内，一个有利的反应函数应使细菌朝着化学引诱剂梯度向上移动；从长期来看，细菌应聚集在化学引诱剂浓度的峰值处。令人惊讶的是，这两个标准相互冲突，以至于当一个性能标准最有利时，另一个则不利。由于这两种行为在生物学上都具有相关性，我们将这两种行为纳入一个复合优化中，得出一个与实验测量结果非常相似的反应函数。我们的工作表明，细菌趋化反应函数可以从简单的行为考虑中推导出来，并揭示了反应函数如何对趋化性能做出贡献。
